Quick effective CEFR level evaluation of complete documents: Integrated readability appraisal of text and graphics with the L-scale algorithm

Readability formulas were invented about a century ago. They are intended as a simple measurement tool for evaluation of the complexity of a written text. Linguistic scientists, mathematicians, editors and software engineers have since then created many different formulas. They are either generally applicable to a specific language or to a business segment. For the readability of a document, its text part is crucial, though not all. The contribution of graphics to readability is relatively small, yet overestimated in many cases. This common misinterpretation results in ineffective investment in expensive ‘over the top’ graphics and even in safety hazards. Web pages and safety documentation are often presumed to be more readable with the simple addition of graphics rather than by writing better readable text. This is a safety threat to workers and it limits the efficacy of, for example, medical information for citizens. Linguistic research indicates that there are nine key parameters that determine the readability of a document. These are used in the ‘L-scale’ algorithm. Incorporated in an automated software tool, on line or in a word processing package, this algorithm quantifies readability of both text and graphics components in digital documents and calculates an effective CEFR readability level.